Book About Concentration Camps in WWII (Female Protagonist)

Hello, I know there are more than a few books about the lives in concentration camps during World War II. This one has a female protagonist. I can't remember much aside from her nearly losing all hope near the end of the book while digging ditches and sinking down into the muddy bank of the ditch. I believe at one point, she contracts an infection and is given rudimentary care. I also recall her talking about riding the rail car to the camp. I read this back in 2002 so I may have forgotten a lot of details. But I'm looking for the title so I can buy it again. Thanks!